Combustion studies using pure compounds as fuels under simple, well characterized combustion conditions will serve to identify the major mutagens produced by combustion and to provide basic data on the processes responsible for their formation and destruction. These processes will be studied using an intensely mixed "stirred reactor" combustion zone followed by a turbulent flow in a post flame duct. This combustor provides well defined combustion conditions with the major characteristics of many practical combustors. Information on both radical and stable species will be obtained with a molecular beam forming instrument and on-line mass spectrometry. Fluoranthene and cyclopenta (cd) pyrene have been identified as the major hydrocarbon mutagens produced. However, we also observe a substantial ability of the effluent material to mutate bacteria in the absence of an exogenous xenobiotic metabolizing system. The chemicals responsible for this activity are more polar than PAH, which suggests nitrogen- and oxygen-containing PAH derivatives. Identification of the compounds contributing to this mutagenicity and the circumstances responsible for their formation are major goals of this proposal. Measurement of concentration of the reacting species over a broad range of conditions will provide the basis for establishing quantitative kinetic models of the formation and destruction of mutagens in both frame zones and in zones where formation takes place via oxidative pyrolysis. This information will be applied toward the goals of establishing the sources of mutagens in practical systems and development of guidelines for avoidance of mutagens emission.